Typically, a header for a harvesting machine includes a cutterbar which is operable to cut standing crop as the machine moves forward and a rotatable reel which carries tines to engage the standing crop and sweep it towards the cutterbar for cutting and then carry the cut material towards an auger before releasing it. The auger usually consolidates the cut crop material centrally of the header before it is passed to the body of the machine for processing. The distance between the cutterbar and the auger can depend on the type and condition of the crop to be harvested. Therefore, some header types have been provided with a cutterbar mounted to a forwardly extendable cutting table, enabling the operator of the harvesting machine to adapt its configuration when the crop condition or type changes.
When harvesting down crops, i.e., crops that are not standing in a normal upright position, the relationships between the reel, the cutterbar and the auger can be important and, in general, the reel should be disposed so that the path described by the outer ends of the tines first enters the down crop forwardly of the cutterbar and below the level thereof for lifting the crop, then sweep closely over the cutterbar and finally pass in close proximity along the auger.
Headers are known in which the cutterbar is vertically flexible along its length so that it can follow local irregularities in the ground. With such headers, it is necessary to be able to adjust the height of the reel relative to the highest point of the cutterbar at any given instant, otherwise the cutterbar is likely to foul the reel on flexing with consequential damage to one or both components. To this end, headers having flexible cutterbars have been fitted with means for automatically adjusting the position of the reel on vertical flexure of the cutterbar.
Similar problems may occur when the cutterbar of an extendable header is set to a forwardmost position. Then the cutterbar will enter into the reel path that is required otherwise for harvesting down crops with a retracted cutting table. The tines or the bars of the reel may then damage the cutterbar or vice versa. Measures must be taken to prevent such interference and limit the path of the reel tines when the header is extended.
One solution to these problems that has been incorporated in Varifeed™ headers sold by New Holland is to incorporate a cam system which adjusts the vertical position of the reel arm. The system includes a cylinder which is linked to the reel arm and has a cam follower in contact with a cam that moves with the cutterbar. As the cutterbar moves in the fore-to-aft direction, the cam moves and contact with the cam follower causes the cam follower to adjust the position of the cylinder, and thus the position of the reel arm. Such a system is effective in single span reels, but has not been found particularly effective in larger headers incorporating split reels which have multiple reel sections connected to multiple cylinders by multiple reel arms.
One particular problem of known systems in split reel headers is coordinating movement of the reel arms together in response to fore-to-aft movement of the cutterbar. Typically, a split reel will be supported at both lateral ends and at the center of the reel by reel arms. The cylinder linked to the center of the re& is not able to be controlled by the cam system described above, while the lateral end cylinders are. Further, while electronically controlling the cylinders has shown promise in coordinating movement of the reel arms, such a system is prone to system lag or malfunction if a fault develops in the wiring.
What is needed in the art is a reliable way to adjust the position of a single span or split reel responsively to fore-to-aft movement of the cutterbar.